1. Field of the Invention
The present invention relates to an electrical connector such as a test socket used for testing of integrated circuit (IC) packages, and particularly to an electrical connector with a metallic stiffener that minimizes the risk of accidental damage to a cover of the connector.
2. Description of the Prior Art
Test connectors are widely used for receiving and testing of IC packages such as land grid array (LGA) chips. A conventional test connector includes a main body, and a plurality of operating levers for actuating lateral movement of the movable plate along the main body. The movable plate is movable between a released state in which the IC package is attached thereon but electrically disengaged terminals in the main body, and a contacting state in which the IC package is electrically engaged with the terminals. U.S. Pat. Nos. 5,186,642 and 5,702,255 disclose this kind of test connector.
FIG. 6 shows a conventional test connector 9. The connector 9 comprises a base 91, a cover 92, a pair of operating members 95, a pair of coil springs 94, a pair of inserting plates 96, and a lid 93. Each operating member 95 comprises a pair of operating levers 950 each defining a receiving hole 951 and a guiding groove 952, a pair of supporting shafts 954 received in the receiving holes 951, and a pair of transmission shafts 955 received in the guiding grooves 952. The base 91 comprises a main body (not labeled) defining a plurality of passageways 910 receiving a plurality of terminals 9 (not shown) therein. The base 91 defines a pair of blind holes 914 for receiving the coil springs 94. Each of opposite ends of the main body defines a pair of retaining grooves 912, for receiving the supporting shafts 954 of the operating members 95. The cover 92 defines a plurality of passages 920 in a main portion thereof, corresponding to the passageways 910 of the base 91. The cover 92 comprises four projections 922 protruding upwardly from four corners thereof. A pair of elongated receiving grooves 924 is defined in opposite ends of the cover 92 respectively, at the projections 922. The receiving grooves 924 are provided for receiving the transmission shafts 955 of the operating members 95. The lid 93 is substantially a rectangular frame, and defines a central opening 930. A pair of receiving recesses (not shown) is defined in bottoms of opposite sidewalls 932 of the lid 93 respectively, for receiving corresponding inserting plates 96 therein.
Referring also to FIG. 7, in assembly, the cover 92 is movably mounted on the base 91. The supporting shafts 954 of the operating members 95 are pivotably received in the retaining grooves 912 of the base 91, and the transmission shafts 955 of the operating members 95 are pivotably received in the receiving grooves 924 of the cover 92. The inserting plates 96 are mounted on the operating members 95, and are fixed in the recesses of the lid 93. The coil springs 94 are mounted between the base 91 and the lid 93. The lid 93 is thereby engaged with the operating members 95 and movably mounted on the base 91.
In use, the lid 93 is pushed downwardly by a robot or an operator's hand (not shown), with corresponding force being applied to the operating members 95. The operating members 95 drive the cover 92 to move horizontally in a direction toward one of the ends of the base 91 via the transmission shafts 955. When the lid 93 has reached a bottommost position, the coil springs 94 are compressed, and the cover 92 is urged to be in an open state. In the open state, an IC package (not shown) can be attached on the cover 92, with leads of the IC package passing through the passages 920 of the cover 92 and being received in the passageways 910 of the base 91 with zero insertion force (ZIF). That is, when the IC package is attached on the cover 92 in the open state, the leads of the IC package are not in mechanical or electrical engagement with the terminals of the base 91. When the downward pushing by the robot or the operator's hand is released, the coil springs 94 decompress, and the cover 92 is driven horizontally in an opposite direction toward its original position. The leads of the IC package thereby mechanically and electrically engage with the terminals of the base 91. In this position, the cover 92 is secured to be in a closed state.
In the conventional connector 9, if a downward force pushing on the lid 93 is insufficient, the cover 92 is driven only part of the way toward the open state. When the IC package is then attached on the cover 92, the leads of the IC package are received in the passageways 910 and interfere with the terminals of the base 91. The leads and the terminals are thus liable to sustain damage. In addition, even when the downward force is sufficient, the shafts 955 are driven to respective endmost portions of the guiding grooves 952, whereat respective walls of the operating levers 950 apply forces on the shafts 955. Smooth movement of the shafts 955 is retarded and interrupted by such forces. Thus, smooth movement of the cover 92 along the base 91 is disrupted, which can result in damage to the leads of the IC package and the terminals of the base 91. Furthermore, in the open state, if the downward force is released suddenly, the coil springs 94 rapidly decompress and drive the lid 93 upwardly, and the cover 92 is quickly driven to the closed state. When this happens, the leads of the IC package enter the terminals of the base 91 with great speed and force, and the leads and the terminals are liable to sustain damage.
In addition, When the downward force applied on the lid 93 is unduly great, the force will be delivered to the cover 92 via the transmission shafts 955. Because the cover 92 is commonly formed from plastic material and only a part of the cover 92 obtains the force, such great force will make the cover 92 crack. When this happens, accurate and reliable engagement between the terminals and the leads of the IC package is decreased.
Therefore, a new test connector which overcomes the above-mentioned problems is desired.